FAQs - AFFFs

Aqueous Film-Forming Foams (AFFFs) effectively extinguish and secure liquid hydrocarbon fires by the following actions:

• Film-forming – the foam forms an aqueous film across the surface of the fire to quickly cut off the oxygen supply and effectively knock down the flames.
• Low surface tension – as the liquid drains from the foam, the surface tension reduces to ensure the foam floats on top of the surface of the liquid fuel.
• Foam expansion – the foam cools the fuel’s surface and creates a stable blanket to suppress the release of flammable vapours.
• Resealing – if the blanket is broken by personnel or equipment, the foam quickly reseals to minimise the risk of re-ignition.

Alcohol Resistant Aqueous Film-Forming Foams effectively extinguish and secure liquid hydrocarbon and polar solvent fires by the following actions:

• Film-forming – the foam forms an aqueous film across the surface of the fire to quickly cut off the oxygen supply and effectively knock down the flames.
• Low surface tension – as the liquid drains from the foam, the surface tension reduces to ensure the foam floats on top of the surface of the liquid fuel.
• Foam expansion – the foam cools the fuel’s surface and creates a stable blanket to suppress the release of flammable vapours.
• Resealing – if the blanket is broken by personnel or equipment, the foam quickly reseals to minimise the risk of re-ignition.
• Membrane forming – in fires involving polar solvents, an insoluble polymer membrane is formed to protect the foam blanket from the solvent.

Firefighting foam concentrates are best stored as supplied in original, unopened containers.

They are also suitable for storage in containers and tanks manufactured from:

• Stainless steel (Type 304L or 316L)
• High density cross-linked polyethylene
• FRP (vinyl ester epoxy resin only)

To prolong the shelf life of any foam concentrate, do not expose to temperature extremes and prevent contamination from foreign materials.

Foam expansion properties will vary depending on several factors including:

• Using salt or fresh water
• Water hardness
• Equipment characteristics
• Equipment flow rate

For example, aspirating devices will produce typical expansion ratios of between 6:1 and 10:1 and non-aspirating devices between 2:1 and 4:1.

Always check your equipment’s operation manual for guidance.

Our foams are available in the following pack sizes:

20 litre, 25 litre, 200 litre, 1000 litre containers and bulk tanks.

Firefighting foams usually have a very long shelf life, provided they are:

• kept within the manufacturer's guidelines
• kept within the manufacturer's temperature limits
• stored in the original and unopened shipping containers.

For example, a shelf life of 10–20 years can be expected for AFFF-LF and AFFF concentrates, if stored correctly. 

For opened containers, this shelf life can be compromised due to factors out-with manufacturers control such as dilution, contamination and extremes of temperature.

Please refer to Safety Data Sheet for preferred storage conditions and guidance.

All AFFF should be contained and disposed of as PFAS-contaminated waste by a licensed waste disposal contractor.

Other produced foams - such a Training Foam and Hi-Ex - can usually be safely disposed of in biological waste water treatment systems. However, it is always best to check the individual product's Safety Data Sheet for information regarding disposal.

As recommended by NFPA 11: 2021, we would advise that a batch compatibility test is performed before mixing foam concentrates from different manufacturers. Please contact us for further information.

The two recognised commissioning standards for produced foam are:

• NFPA 11: 2021 Edition, Paragraph 12.6
• BS EN 13565-1: 2019, Section 5.3

The “acceptable ranges for proportioning percentage” stated in these standards are:

If your produced foam falls outwith these ranges as part of your foam testing protocols, it would be considered a fail; your foam systems proportioning and induction equipment will require recalibration.

"The foam concentrate induction rate of a proportioner... shall be within minus 0 percent to plus 30 percent of the manufacturer’s listed concentrations, or plus 1 percentage point, whichever is less. "

NFPA 11: 2021, Paragraph 12.6.5

Foam concentrates are tested by manufacturers to meet Internationally recognised extinguishment, burnback and proportioning standards.

The three most widely recognised tests are:

These are critical application tests in that foam concentrates are tested to the minimum application rate required to extinguish a fire: a quality foam supplier will supply foam concentrates that meet at least one of these standards. 

For further information, please see our International Standards page.

Foam concentrates are tested by manufacturers to meet Internationally recognised standards that evaluate extinguishment, burnback and proportioning. For further information, please see our International Standards page.

It is mandatory that all foams used in civilian airports must be approved to ICAO Level A, ICAO Level B or ICAO Level C standard.

ICAO Level B

In order to obtain ICAO Level B certification the foam concentrate, once proportioned correctly, must extinguish a 4.5m² hydrocarbon fire within the given specifications (see table below).

The application rate for the ICAO Level B test is 2.5 L/min/m².

ICAO Level C

In order to obtain ICAO Level C certification the foam concentrate, once proportioned correctly, must extinguish a 7.32m² hydrocarbon fire within the given specifications (see table below).

The application rate for the ICAO Level C test is 1.75 L/min/m².

ICAO Level C test has been designed to permit substantially reduced quantities of foam and water to available on fire trucks (for further information, please refer to the OTAC document on Rescue and Fire-Fighting Management of Extinguishing Agents here.)

Comparison of Test Protocol

ICAO Level C places increased emphasis on:

• Impacts of fluctuating water pressure
• ARFF vehicle monitor application rates, i.e. regular produced foam testing.

IMO stands for International Maritime Organization (IMO). It has introduced two testing standards (IMO MSC.1/Circ 1312 and MSC Circ.670) to ensure that foam used at sea is fit for purpose and takes into consideration performance with sea water induction and temperature conditioning (accelerated ageing). The standards are now required by many maritime administrations and classification bodies for foam concentrates to be used on board ships in international waters. This may lead to an administration/classification body stipulating the use of an IMO compliant foam and rejecting the use of a non-compliant fire-fighting foam on board ships.

The IMO standards have arisen as part of the implementation of the SOLAS Convention (Safety of Life at Sea). 

The IMO MSC.532(107) resolution stipulates that, from 1st January 2026, the use of PFOS-containing foams in any fire extinguishing systems is prohibited.

In accordance with IMO MSC.1/Circ.1694 and SOLAS Regulation II-2/10.11, compliance requires confirmation that PFOS concentrations in foam products are below 10 mg/kg (0.001% by weight).

All Aberdeen Foam products listed below comply with these requirements:

PFAS (per- and polyfluoroalkyl substances) are a large group of over 15,000 human-made chemicals.

Manufacturers have used them in everyday products since the 1950s because their chemical properties make them resistant to water, grease and heat.

Examples of products that can include PFAS are:

• Non-stick frying pans
• Waterproof clothing
• Food packaging
• Firefighting foams

For more information on the UK HSE's response to use of PFAS in firefighting foams, please see here.

Yes: here are a selection of organisations and authorities related to the international fire fighting industry.

• Industrial Organisation for Industrial Emergency Services Management (JOIFF)
• Fire Industry Association (FIA)
• Fire Sector Confederation (FSC)
• LASTFIRE
• National Fire Protection Agency (NFPA)
• International Civil Aviation Organization (ICAO)